papers/hanzo-checkout/sections/08-security-analysis.tex

\section{Security Analysis}


\subsection{Threat Model}

We consider adversaries with capabilities:
\begin{itemize}
    \item Network interception (mitigated by TLS 1.3)
    \item Merchant system compromise (mitigated by tokenization)
    \item Replay attacks (mitigated by idempotency keys and timestamps)
\end{itemize}

\subsection{Token Security}

\begin{theorem}[Token Unforgeability]
An adversary without vault access cannot forge a valid token with probability greater than $2^{-128}$.
\end{theorem}

\begin{proof}
Tokens are generated using cryptographically secure random number generation with 128-bit entropy. Without access to the vault's token-to-credential mapping, an adversary must guess both the token ID and its association, which requires $O(2^{128})$ attempts.
\end{proof}